چکیده انگلیسی

Objective
The primary objective was to identify specific groups of patients with a first-episode psychosis based on family history, obstetric complications, neurological soft signs, and premorbid functioning. The secondary objective was to relate these groups with cognitive variables.
Method
A total of 62 first-episode psychoses were recruited from adult and child and adolescent mental health services. The inclusion criteria were patients between 7 and 65 years old (real range of the samples was 13–35 years old), two or more psychotic symptoms and less than one year from the onset of the symptoms. Premorbid functioning (PAS), soft signs (NES), obstetric complications and a neuropsychological battery (CPT, TMTA/TMTB, TAVEC/TAVECI, Stroop, specific subtest of WAIS-III/WISC-IV) were administered.
Results
We found three clusters: 1) higher neurodevelopment contribution (N = 14), 2) higher genetic contribution (N = 30), and 3) lower neurodevelopment contribution (N = 18). Statistical differences were found between groups in TMTB, learning curve of the TAVEC, digits of the WAIS and premorbid estimated IQ, the cluster 1 being the most impaired.
Conclusions
A cluster approach could differentiate several groups of patients with different cognitive performance. Neuropsychological interventions, as cognitive remediation, should be addressed specifically to patients with more impaired results.

مقدمه انگلیسی

In recent years an increasing interest in the assessment of cognitive variables in people with schizophrenia and first-episode psychosis has emerged. The results of most of the studies carried out have demonstrated a neurocognitive deficit in people with schizophrenia and first-episode psychosis. The most prevalent cognitive impairments detected in people with schizophrenia are those related to deficits of memory, executive function and attention (Green, 1996, Hoff and Kremen, 2003, Sharma and Antonova, 2003, Dickinson et al., 2007, Nuechterlein et al., 2008 and Brébion et al., 2012).
Memory and learning problems were among the most studied cognitive variable in first-episode psychosis related to control groups, showing a worse functioning in people with a first-episode psychosis (Bilder et al., 2000, Galderisi et al., 2009, Zanello et al., 2009, Holmén et al., 2010, Jahshan et al., 2010 and Zabala et al., 2010). O'Connor et al. (2009) point out that verbal memory is affected in people with a first episode psychosis regardless of the premorbid IQ. Moreover, Galderisi et al. (2009) found that people with a first episode psychosis scored worse than healthy controls in processing speed, motor dexterity, and cognitive flexibility tasks. Zabala et al. (2010), in a sample of early-onset first-episode psychosis, add attention to this list.
However, not all people with a first-episode psychosis performed worse than controls in cognitive assessment (Leeson et al., 2010 and Bartholomeusz et al., 2011). Some of this variability may be explained by the presence of latent subgroups that differ in etiology and key neurobiological underpinnings. Identifying these subgroups could help to improve the treatment of schizophrenia and first-episode psychosis (Jindal et al., 2005).
According to the neurodevelopment hypothesis, the etiology of psychosis may involve pathological processes, caused by both genetic and environmental factors that begin before the brain approaches its adult anatomical state in adolescence (Fatemi and Folsom, 2009). Several markers of congenital alterations indicative of neurodevelopmental insults have been found. It is well documented that there are higher rates of neurological soft signs in patients with schizophrenia than in healthy controls (Heinrichs and Buchanan, 1988); moreover this higher prevalence has been observed in first-episode patients (Bombin et al., 2005, Compton et al., 2007, Ruiz-Veguilla et al., 2008 and Mayoral et al., 2012). In addition, there is consistent evidence showing that a large number of people affected by the spectrum of psychotic disorders manifest poor social and academic adjustment prior to initiation of the disease (Allen et al., 2001, Norman et al., 2005 and Monte et al., 2008).
Emerging evidence points to schizophrenia as a familial disorder with a complex mode of inheritance and variable expression (Meltzer and Fatemi, 2000). Moreover, Gottesman et al. (2010) found a higher familial risk when one or two parents presented a mental disorder. The study also differentiated a higher risk in the offspring of couples diagnosed with a psychiatric disorder than in children with only one affected parent. While familial risk factors account for a significant rate of predisposition to schizophrenia, there is also evidence of an important environmental contribution. Obstetric complications are among the most studied environmental indicators of risk for schizophrenia (Clarke et al., 2006).
All the variables described above are associated with schizophrenia and psychotic disorders and can be detected prior to onset of symptoms. They may, in part, help us to explain the heterogeneity of spectrum of psychotic disorders. To explore this we chose to use an approach based on cluster analysis. K-means clustering has been used to examine the heterogeneity of psychotic disorders (Lee et al., 2011 and Dawes et al., 2011; Ruiz-Veguilla et al., 2008 and Richards et al., 2008). However, no previous studies have used cluster analysis either for grouping patients according to factors prior to onset of illness or for grouping patients in samples of first-episode of psychosis.